JP4094202B2 - Single crystal pulling apparatus and single crystal pulling method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a single crystal pulling apparatus and a single crystal pulling method for pulling a single crystal such as silicon.
[0002]
[Prior art]
In general, in a method in which a thin dash neck (hereinafter referred to as a neck portion) is formed under a seed crystal (seed), and then a single crystal (body portion) having a large diameter and a large weight is formed directly under the neck portion, There is a possibility that the portion cannot withstand the heavy load of the single crystal and breaks. Therefore, as a method to prevent this, an enlarged diameter portion is formed under the neck portion, a small diameter portion (constricted portion) is formed under the enlarged diameter portion, and the enlarged diameter portion above the constricted portion is claw-shaped. The diameter-enlarged part is supported by the diameter-enlarged part support member, while gradually moving the load from the neck part to the diameter-enlarged part while pulling up the single crystal at a predetermined speed, and then completely shifting to the diameter-enlarged part support A method of lifting only with support has been proposed.
[0003]
As a mechanism for realizing this method, for example, as shown in Japanese Patent Publication No. 7-515, Japanese Patent Application Laid-Open No. 7-172981, Japanese Patent Application Laid-Open No. 11-92279, etc., a seed crystal provided on the chamber is pulled up. There is known a method in which a diameter enlarged portion pulling mechanism is further provided on the mechanism, and these seed crystal pulling mechanisms, that is, a method of synchronizing the pulling speeds of the neck load and the diameter enlarged portion pulling mechanism with each other.
[0004]
FIG. 4 is a side view showing one of a plurality of embodiments of the single crystal pulling apparatus shown in the above-mentioned Japanese Patent Application Laid-Open No. 11-92279. In FIG. 4, a seed crystal holder 2 is attached to the tip of the pulling shaft 1, and a seed crystal 3 is attached to the seed crystal holder 2. The shaft 1 is a stationary part and can be rotated by a motor 28 provided in a first structure 24 that can move up and down with respect to a mechanical chamber 18 that constitutes a vacuum chamber that houses a single crystal 7 to be grown and a quartz crucible 15. It is arranged in. The first structure 24 has a screw portion 26 (nut portion) in which a female screw is provided. The screw portion 26 includes a rod 22 with a male screw that is rotated by a motor 20 attached to the mechanical chamber 18. It is screwed. Therefore, the first structure 24, the motor 28 attached to the first structure 24, and the shaft 1 can move up and down with respect to the quartz crucible 15 by the rotation of the motor 20. That is, the pulling shaft 1 is rotatably attached to the first structure 24, and the shaft 1 is rotated by the motor 28 placed on the first structure 24. Below the first structure 24, a rotating substrate 34 </ b> A (second structure) fixed to the shaft 1 and rotating together with the shaft 1 is provided. The rotary substrate 34A is always at a constant vertical position with respect to the first structure 24.
[0005]
A motor 30 is mounted on the rotating substrate 34A, and the threaded rod 32 is rotated. The threaded rod 32 is movable in the vertical direction with respect to the rotating substrate 34A, and is screwed into a female thread portion 36 that is rotatably held on a support shaft 72 that is rotatably held. Accordingly, the support shaft 72 moves up and down with respect to the rotating substrate 34A and the first structure 24 by rotating the motor 30 attached to the rotating substrate 34A.
[0006]
The support shaft 72 extends to the inside of the mechanical chamber 18 via a rotary table 80 that is rotatably attached to the upper portion of the mechanical chamber 18 via a bearing 82, and a support that is a dish-like member is provided at the lower end thereof. A body 70 is attached. In FIG. 4, a balance weight 90 is provided on the rotary substrate 34 </ b> A together with its adjustment screw 92, and seal members 84, 86, and 88 are provided on the rotary table 80. Further, the lifting shaft 1 is provided with a shock absorber 60.
[0007]
The conventional apparatus of FIG. 4 operates as follows. When the preparation for pulling is completed, first, the motor 20 is operated to lower the first structure 24, so that the shaft 1 is pulled downward in the drawing to bring the seed crystal 3 into the surface of the Si melt 10 in the quartz crucible 15. Soak it in and let it fit. At this time, the support body 70 stands by at a position where the tip does not come into contact with the Si melt 10, and the support body 70 is in a non-supporting position so as not to come into contact with the enlarged diameter portion 12 being pulled up.
[0008]
Next, after a predetermined time has elapsed, the motor 20 is rotated in the reverse direction to the above, the first structure 24 is raised, and the seed crystal 3 is pulled upward at a relatively high speed so that the diameter is 3 to 3 below the seed crystal 3. After the neck portion 11 having a small diameter of 4 mm is formed, and then the pulling speed is relatively slow to form the supporting diameter expanding portion 12 below the neck portion 11, the pulling speed is relatively high to increase the diameter expanding portion. The constricted portion is formed under 12, and then the formation of the crystal body portion 7 is started.
[0009]
Next, the motor 30 is rotated to a height at which the support body 70 is located below the enlarged diameter portion 12. Thereafter, the motor 40 is rotated to rotate the support shaft 72 to a predetermined position so that the support 70 is positioned directly below the diameter enlarged portion 12. Next, the motor 30 is further rotated to raise the support body 70 to a speed faster than the lifting speed of the lifting shaft 1. When the support body 70 holds the lower end of the enlarged diameter portion 12 in this way, the motor 30 is stopped. Thereafter, the first structure 24 and the rotating substrate 34A (second structure) are raised together by the motor 20, so that the seed crystal 3 and the support 70 are raised at the same speed. .
[0010]
FIG. 2 shows changes over time in the load W1 applied to the neck and the load W2 applied to the enlarged diameter portion supported by the enlarged diameter portion when the neck load is pulled up. The crystal weight W increases in proportion to the pulling time t. In FIG. 2, only the neck load is pulled up to time t1, and therefore the load W1 due to the neck load is increased in proportion to time t (W1 = W, W2 = 0). Then, when the diameter enlarged portion support is started from time t1 and the load movement from the neck load to the diameter enlarged portion support is gradually started between times t1 and t2, the load W1 decreases with the passage of time t during this period. However, the load W2 by the diameter enlarged portion support increases. Next, when the load movement is completed at time t2, W1 = 0 and W2 = W as shown by the solid line thereafter.
[0011]
[Problems to be solved by the invention]
However, when the load movement is performed as in the above-described conventional apparatus, and the seed crystal pulling mechanism and the diameter enlarged portion pulling mechanism are integrated by a single drive source and the pulling speeds are synchronously pulled, the load movement completion time t2 In this case, the claw-like member may be deformed downward by a load. Due to this deformation, as indicated by broken lines W1 ′ and W2 ′ in FIG. 2, the load increase is not applied to the diameter enlarged portion support side but applied to the seed crystal portion support side (W1 ′> 0, W2 ′ < W2), there is a problem in that the pulling speed changes, or the crystal being pulled is vibrated, causing problems. This problem occurs when the claw-like member is deformed by about 0.1 mm.
[0012]
As a method for solving this problem, for example, in Japanese Patent Laid-Open No. 11-92279, an extension member is provided on the mechanism side for pulling up the seed crystal in order to transfer the load increase to the diameter-enlarged portion pulling mechanism side. A method has been proposed. However, this method has a problem that the cost is increased correspondingly, and there is a problem that a large restriction is imposed on the apparatus design to attach the mechanism.
[0013]
In view of the above-described problems of the conventional example, the present invention is configured to synchronize the seed crystal pulling mechanism and the enlarged diameter portion pulling mechanism, and gradually shifts the load from the neck load lifting to the enlarged diameter portion support without providing a special mechanism. An object of the present invention is to provide a single crystal pulling apparatus and a single crystal pulling method that can be applied to a diameter enlarged portion supporting member without being applied to the neck portion while an increase in load is applied to the neck portion. .
[0014]
[Means for Solving the Problems]
In order to achieve the above-described object, the present invention completely shifts from the lifting due to the neck load to the diameter-enlarged portion support, and when the load due to the diameter-enlarged portion support should be 100% , the diameter- enlarged portion supporting member is raised. The speed is relatively higher than a predetermined pulling speed.
[0015]
That is, according to the present invention, the rotating means for rotating the seed crystal holder for supporting the seed crystal above the crucible capable of holding the molten crystal, and the seed for pulling up the seed crystal by pulling up the seed crystal holder while controlling the speed. A crystal pulling means, which can be rotated together with the seed crystal holder, and can be moved in the vertical direction as the seed crystal holder moves in the vertical direction, and is pulled below the seed crystal by the pulling by the seed crystal pulling means. A supporting means for supporting the lower end of the formed enlarged diameter portion from below; and the position of the supporting means is controlled in the vertical direction with respect to the seed crystal holder. Crystal holding position control means for moving the supporting means up and down integrally with the seed crystal holder by transmitting power; and In the single crystal pulling apparatus having a support means moving means for moving and a second position for supporting a first position not supporting an end of the lower end of the larger diameter portion,
In the single crystal pulling step, the transition from the neck load where the load of the single crystal is applied to the neck portion completely to the pulling by the diameter enlarged portion support, and the load due to the diameter enlarged portion support should be 100% in the pulling speed of the relative to the larger diameter portion supporting member faster than the pulling speed by the neck load, and after pulling or only a predetermined distance after a predetermined time has passed, based on a predetermined pulling speed Return speed control means,
A single crystal pulling apparatus is provided.
[0016]
According to the present invention, the rotating means for rotating the seed crystal holder for supporting the seed crystal above the crucible capable of holding the molten crystal, and the seed for pulling up the seed crystal by pulling up the seed crystal holder while controlling the speed. A crystal pulling means, which can be rotated together with the seed crystal holder, and can be moved in the vertical direction as the seed crystal holder moves in the vertical direction, and is pulled below the seed crystal by the pulling by the seed crystal pulling means. A supporting means for supporting the lower end of the formed enlarged diameter portion from below; and the position of the supporting means is controlled in the vertical direction with respect to the seed crystal holder. Crystal holding position control means for moving the support means up and down integrally with the seed crystal holder by transmitting power; and the support means at the lower end of the diameter enlarged portion In the single crystal pulling method using the single crystal pulling apparatus having a support means moving means for moving between a first position not supporting the second position for supporting the lower end of the larger diameter portion,
In the single crystal pulling step, the transition from the neck load where the load of the single crystal is applied to the neck portion completely to the pulling by the diameter enlarged portion support, and the load due to the diameter enlarged portion support should be 100% in the steps of the pulling speed of the relative to the larger diameter portion supporting member faster than the pulling speed by the neck load,
A step of returning to the original predetermined lifting speed after a predetermined time has elapsed or after a predetermined distance has been lifted,
A method for pulling a single crystal is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a single crystal pulling apparatus according to the present invention, and FIG. 2 is a graph showing changes with time of a load in the case of pulling by a neck load and a load by supporting a diameter enlarged portion.
[0018]
In FIG. 1, a seed holder 2 is attached to the lower end of a crystal pulling shaft (also simply called a shaft) 1, and a seed (seed crystal) 3 is attached to the seed holder 2. The shaft 1 is lowered by the controller 16, the raising / lowering motor M <b> 1 and a rotating motor (not shown) until the seed 3 is immersed in the polycrystalline melt 10, and then pulled up while rotating. Further, the diameter-enlarged-portion support member 4 described later is moved up and down and rotated by a controller 16, a lifting motor M2 and a rotating motor (not shown). In FIG. 1 and FIG. 3 to be described later, the structure for pulling up the seed holder 2 and the structure for pulling up the diameter-enlarged portion support member 4 are shown separately, but these are the same as FIG. 4 showing the structure of the prior art. Similarly, interrelated, are configured to interlock together in basic manner.
[0019]
With respect to the pulling speed v1 of the shaft 1, a narrow neck portion 11 is formed under the seed 3, a diameter enlarged portion 12 is formed under the neck portion 11, and a small diameter portion (constriction) 13 is formed under the diameter enlarged portion 12. And is controlled so that a part of the cylindrical body portion 14 is formed below the small-diameter portion 13, and is approximately inversely proportional to the diameter. The pulling speed v1 during the formation of the body portion 14 having a constant diameter varies slightly depending on the requirements such as temperature, but here, for the sake of simplicity, the pulling speed v1 is always described as a constant speed (v1 = v0).
[0020]
Up to this point, the shaft is pulled up only by the shaft 1 (only the neck portion is supported) (W1 = W, W2 = 0 in FIG. 2). Thereafter, the diameter-enlarged portion support member 4 is raised with respect to the constricted portion 13 below the diameter-enlarged portion 12, and is transiently engaged at the same pulling speed v2 = v1 (and the same rotational speed) as the shaft 1, Thereafter, the lifting speed v2 of the enlarged diameter portion supporting member 4 is controlled to be higher than the lifting speed v1 of the shaft 1 to gradually shift from the neck portion support to the enlarged diameter portion support (W1 + W2 = W in FIG. 2). In the present invention, at the time t2 when the load movement is completed and W1 = 0 and W2 = W, even if the enlarged diameter portion support member 4 is deformed by the load, W1 = 0 and W2 = W. The pulling speed v2 of the diameter-enlarged portion support member 4 is relatively faster than the pulling speed v1 of the shaft 1 at a predetermined acceleration or for a predetermined time or a predetermined distance, and after a predetermined time has elapsed or a predetermined distance Then, the speed is returned to the original predetermined speed v0.
[0021]
As an example of a method of relatively increasing the pulling speed v2 of the diameter-enlarged portion support member 4 higher than the pulling speed v1 of the shaft 1, the shaft 1 is maintained at a constant pulling speed (v1 = v0), and the diameter is expanded. There is a method of increasing the pulling speed v2 of the part support member 4 (v2> v0). That is, the pulling-up speed of the enlarged diameter portion supporting member 4 is made faster than the predetermined pulling speed at the normal time at a predetermined acceleration or for a predetermined time or a predetermined distance. In addition, as shown with a dotted line in FIG. 1, it is a preferable aspect that the seed 3 is configured to be movable only in the upward direction of the seed holder 2. As another example, as shown in FIG. 3, the seed holder 2 a can be supported by a crystal pulling wire (also simply referred to as a wire) 1 a instead of the shaft 1. In this case, at the time t2 when W1 = 0 and W2 = W, the pulling speed v1 of the wire 1a is set to 0, and at a predetermined acceleration or for a predetermined time or a predetermined distance, The pulling speed v2 is made higher than the predetermined speed v0, and when the predetermined time elapses, it is returned to the original predetermined speed v0. That is, the pulling speed due to the neck load is reduced at a predetermined deceleration or for a predetermined time or a predetermined distance, or the pulling due to the neck load is stopped.
Further, as a method of detecting the time t2 when W1 = 0 and W2 = W, weight sensors are provided on both or one of the shaft 1 (or wire 1a) side and the enlarged diameter portion supporting member 4 side. In the case where the weight sensor is provided only on the shaft 1 (or wire 1a) side, W1 = 0 may be detected. In addition, a predetermined acceleration or a predetermined time or a predetermined distance for increasing the pulling speed v2 of the diameter-enlarged portion support member 4 to be higher than the predetermined speed v0 is obtained in advance for each load W2 at the load transition completion time t2, for example. This can be detected and determined by a weight sensor provided on the side support member 4 side.
[0023]
【The invention's effect】
As described above, according to the present invention, the lifting speed of the diameter- enlarged portion support member is increased at the time when the load due to the diameter-enlarged portion support should be 100% after the lifting due to the neck load is completely shifted to the diameter-enlarged portion support. Since the speed is relatively higher than the predetermined pulling speed, the load increase when the load is gradually shifted from the neck portion support to the enlarged diameter portion support is applied to the neck portion without providing a special mechanism. It is possible to ensure that it is applied to the enlarged-diameter support member without any problem.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of a single crystal pulling apparatus according to the present invention.
FIG. 2 is a graph showing a change with time of a load due to a neck load and a load due to support of the enlarged diameter portion.
FIG. 3 is a configuration diagram showing a modification of the single crystal pulling apparatus of FIG. 1;
FIG. 4 is a side view showing an example of a conventional single crystal pulling apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Crystal pulling shaft 1a Crystal pulling wire 2, 2a Seed holder 3 Seed (seed crystal)
4 Diameter-enlarged portion support member 10 Melt 11 Neck portion 12 Diameter-enlarged portion 13 Constricted portion 14 Body portion 16 Controller M1, M2 Motor

Claims (10)

Rotating means for rotating a seed crystal holder that supports the seed crystal above a crucible capable of holding a molten crystal, seed crystal pulling means for pulling up the seed crystal by pulling up the seed crystal holder while controlling the speed, and the seed A diameter-enlarging portion that can be rotated together with the crystal holder and can be moved in the vertical direction along with the vertical movement of the seed crystal holder, and formed below the seed crystal by pulling up by the seed crystal pulling means. A supporting means for supporting the lower end from below, and controlling the position of the supporting means in the vertical direction with respect to the seed crystal holder, and when not in position control, by transmitting the power of the seed crystal pulling means, Crystal holding position control means for moving the supporting means up and down integrally with the seed crystal holder, and a first position where the supporting means does not support the lower end of the diameter-enlarging portion. In the single crystal pulling apparatus having a support means moving means for moving and a second position for supporting the lower end of the larger diameter portion and,
In the single crystal pulling step, the transition from the neck load where the load of the single crystal is applied to the neck portion completely to the pulling by the diameter enlarged portion support, and the load due to the diameter enlarged portion support should be 100% in the pulling speed of the relative to the larger diameter portion supporting member faster than the pulling speed by the neck load, and after pulling or only a predetermined distance after a predetermined time has passed, based on a predetermined pulling speed Return speed control means,
A single crystal pulling apparatus comprising: 2. The single crystal according to claim 1, wherein the speed control unit makes the pulling-up speed of the diameter-enlarged portion support member faster than the predetermined pulling speed at a predetermined acceleration or for a predetermined time or a predetermined distance. Lifting device. 2. The speed control means according to claim 1, wherein the speed control means decelerates the pulling speed by the neck load or stops the pulling by the neck load at a predetermined deceleration or for a predetermined time or a predetermined distance. Single crystal pulling device. A means for detecting the load of the single crystal applied to the neck when the neck load is pulled up; and the speed control means is configured such that when the load becomes “0”, the load by the enlarged diameter portion support is 100%. The single crystal pulling apparatus according to claim 1, wherein the single crystal pulling apparatus is determined to be a point in time. Rotating means for rotating a seed crystal holder that supports the seed crystal above a crucible capable of holding a molten crystal, seed crystal pulling means for pulling up the seed crystal by pulling up the seed crystal holder while controlling the speed, and the seed A diameter-enlarging portion that can be rotated together with the crystal holder and can be moved in the vertical direction along with the vertical movement of the seed crystal holder, and formed below the seed crystal by pulling up by the seed crystal pulling means. A supporting means for supporting the lower end from below, and controlling the position of the supporting means in the vertical direction with respect to the seed crystal holder, and when not in position control, by transmitting the power of the seed crystal pulling means, Crystal holding position control means for moving the supporting means up and down integrally with the seed crystal holder, and a first position where the supporting means does not support the lower end of the diameter-enlarging portion. In the single crystal pulling method using the single crystal pulling apparatus having a support means moving means for moving and a second position for supporting the lower end of the larger diameter portion and,
In the single crystal pulling step, the transition from the neck load where the load of the single crystal is applied to the neck portion completely to the pulling by the diameter enlarged portion support, and the load due to the diameter enlarged portion support should be 100% in the steps of the pulling speed of the relative to the larger diameter portion supporting member faster than the pulling speed by the neck load,
A step of returning to the original predetermined lifting speed after a predetermined time has elapsed or after a predetermined distance has been lifted,
A method for pulling a single crystal, comprising: Pulling speed before Symbol relatively step of faster pulling speed the pulling speed by the neck load of the larger diameter portion support member, a predetermined acceleration or a predetermined time or a predetermined distance, the larger diameter portion supporting member The pulling speed due to the neck load is reduced at a predetermined deceleration or for a predetermined time or a predetermined distance, or the lifting due to the neck load is stopped. The single crystal pulling method according to claim 5. The single crystal pulling-up method according to claim 6, wherein the predetermined distance is determined in advance, and feedback control of pulling up the diameter-enlarged portion supporting member is performed by monitoring a position of the diameter-enlarged portion supporting member. Method. The single crystal pulling method according to claim 6, wherein only a moving speed and a moving time of the diameter enlarged portion supporting member are controlled. Detecting the load of the single crystal in the pulling by the neck load;
Determining the time when the load becomes “0” as the time when the load due to the support of the enlarged diameter portion should be 100%,
The method for pulling a single crystal according to claim 5, comprising: Claims, characterized in that the steps of the pulling speed before Symbol relatively the larger diameter portion supporting member faster than the pulling speed by the neck loads, and returning to a predetermined pull rate of the original is repeated a plurality of times 5. The single crystal pulling method according to 5.

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